Range and phase finder for synchronous telegraph systems



1941- J. A. SPENCER 2,265,254

RANGE AND PHASE FINDER FOR SYNCHRONOUS TELEGRAPH SYSTEMS Filed April 29,1939 INVENTOR. JAMES A. SPENCER ATTORNEY.

Patented Dec. 9, 1941 UNITED STATES PATENT OFFICE RANGE AND PHASE FINDERFOR SYNCHRO NOUS TELEGRAPH SYSTEMS James A. Spencer, Teaneck, N. J.,assignor to Radio Corporation of America, a corporation of DelawareApplication April 29, 1939, Serial No. 270,717

3 Claims.

marking impulses comprehended in an equal length code signal may beselectively applied to the decoding apparatus for actuating a printer.

Inorder that the receiving apparatus, especially the receivingdistributor, may be correctly synchronized and phased with respect tothe incoming signals it has been necessary heretofore to observe theoperation of the printer while controlling the distributor orientation.In such cases it is found advantageous to employ predetermined testsignals and to adjust the orientation of the distributor segments withrespect to the distributor brush by reference to the effects producedupon the printer. It is frequently desirable, however, to locate theprinter at some point remote from the distributor so that it is quiteinconvenient, if not impossible, to follow the printer operation whileattempting to orient i the distributor. Furthermore, it has been foundnecessary to employ two distinct types of test signals,. one for phasingand the other for range finding. By phasing is meant the assignment ofeach of the multiplex signals to appropriate printer units. By rangefinding is meant the more refined orientation of the distributorsegments so that the marking impulses shall fall as nearly as possibleupon the center portions of each distributor segment.

It is an object of my invention to provide phase and range findingapparatus for use in synchronous multiplex telegraph operation such thatan indication may be had in close proximity to the receivingdistributor. The indications so provided may then be utilized forpurposes of orienting the distributor with respect to the incomingsignals.

It is another object of my invention to provide a phase and rangeindicating device in combination with a synchronous telegraph receivingdistributor and in combination with other telegraph apparatus such thatsynchronous correction of the receiving distributor may be monitored.

Other objects and advantages of my invention will be made clear by thefollowing description when read in view of theaccompanying drawing, thesole figure of which represents diagrammaticallythe essential elementsof a preierred embodiment and more particularly the circuit arrangementwhich is relied upon for performing the functions of the apparatus.

Referring to the drawing, I show therein in blockdiagram a conventionallocking circuit [0 which has input leads and an output circuit feedingto the polarized relay 2|. The incoming signals may be derived from aline or a radio channel. The details of the locking circuit are notshown as they are well understood in this art. They usually comprise anarrangement of. electron discharge tubes having a trigger action suchthat very short "impulses representing the components of a code signalare shaped into more prolonged controlling impulses of square waveformation suitable for actuating a relay such as that shown at 2|. Thisrelay may be polarized as indicated conventionally or it may be a biasedrelay of any suitable type. The armature 22 of this relay is controlledfor impressing marking and spacing impulses upon a distributor ring 9,these impulses being derived from any suitable direct current source 23.The distributor as shown includes in addition to the ring 9 a pluralityof segments one series of which is numbered from 1 to 7 inclusive. Thesesegments are identified with the respective units of a uniform lengthcode signal. Other segments in the outer ring of the distributor may beemployed, if desired, to distribute the elements of other code signalsto their appropriate printer units as, for example, when the system isused in multiplex telegraphy. The distributor as shown has 21 conductivesegments in the outer ring and hence is suitable for synchronoustransmission of code signals such as for simultaneously actuating threeseparate printers.

According to conventional practice the solid ring 9 and the segments ofthe outer ring are all mounted on a common face plate 24. Hence thesegments may be oriented either clockwise or counter-clockwise to adjustthe effective phase of the brush 8, without varying the speed of thelatter.

The conductive segments of the distributors are separated by insulationsegments which subtend sufficient arcs so that when the distributor isproperly phased the brush 8 will be passing over an insulation segmentwhile the armature 22 is allowed time to travel from one to the other ofits companion contacts. Although the armature travel time is very smallit is important that it shall take place as nearly as possible at themid-point of passage of the brush 8 over an insulation segment.

Since thebircuit arrangement for one printer is the same as that of theothers only the circuits appropriate to one printer and its associatedapparatus have been shown in the drawing.

The brush 8 mounted on a brush arm is synchronously driven by a suitablemotor, not shown. The outer ring of distributor segments may be rotatedwith respect to the stator of the motor for the purpose of properlyorienting the distributor with respect to the incoming signals.

correcting device, in which case the brusharm would be advanced orretarded according to requirements.

Each of the segments l to inclusive co;

nected respectively with an appropriate magnet II to I! inclusiveconstituting a portion of the conventional decoding means which maybeemployed in a receiving telegraph printer. The

"details of the printer are not otherwise shown as they are well knownin the art. It is also understood how the magnets H to I! inclusive maybe caused to actuate different code bars, or devices for character typeselection, thereby to control the operation of the printer in responseto the received signals.

segment.

Each of the segments 2, 4 and 6 is connected by a branch circuit to oneof the glow discharge tubes 32, 34 and 36 respectively. These branchcircuits are completed through the glow discharge tubes to a commonreturn circuit which may be grounded, if desired.

In the operation of my invention for testing the distributor orientationand for adjusting the same, it is desirable that a test signal betransmitted such that three marking elements shall be uniformly spacedapart by intervening spacing units of the same code signal. When such 'atest signal is applied to only one particular channel, which is selectedfor test purposes, the resulting indications are sufiicient for properlyorienting the distributor. If the test signal falls haphazardly upon thedistributor segments, it is unlikely that any of the glow tubes 32, 3dand 36 will be ignited. The distributor ring is, therefore, rotated withrespect to the field of the motor until all three of the glow tubeslight up in response to the uniformly spaced marking ele- -ments of thetest signal. the marking impulses it is definitely known that By thisresponse to the correct phase has been found. In other words, it can beseen that the signal itself is confined to that part of the distributorbetween the index points it and 19. Printer code signals subsequentlytransmitted on each of the channels will then be fully spread over thedistributor segments appropriate thereto, and successive control of therespective printer units will be conformed to the channel separation ofthe code signals. If the test signal were to be applied so as to overlapthe arc of the distributor ring between the index points l8 and I9,either no lamps would be 10. As an alternative the motor stator may bemade rotatable in response to the'operation' of a phase" lighted orpossibly only one or two of the same would be observed to glow.Correspondingly, if the signal were to be delayed so that it overlappedthe two arcs comprehended from the index points from l8 through H! to25], then one or both of the lamps 34 and 36 might be ignited or elsenone at all. It is clear, therefore, that perfect phasing of thedistributor is indicated only when all three of the lamps 32, 34 and 36are ignited.

It will be understood that the glow discharge tubes may be'of thegaseous type, which comprehends, for example, neon lamps. In practicethe brush passes over the different segments of the distributor sorapidly that it rotates through one revolution in .less time than thepersistence of vision, or atleast it is only possible for an observer tonote that the lamps when ignited produce a flickering eiiect. This istrue even though it is a characteristic of the neon lamp to becompletely extinguished at the instant when it ceases to pass current.

When the invention is to be used for range finding, the distributor ringmay be oriented either clockwise or counter-clockwise until,theoretically, all three lamps are extinguished by such orientation. Inpractice, due to the effects of signal distortion, only one of the lampsis completely extinguished while the other two exhibit a dim flicker.The ring may then be rotated in the opposite direction through the arewhich enables the lamps to be fully ignited and until they becomepractically extinguished again. The length of the arc of distributorsegment rotation which represents continuous ignition of the neon lampsrepresents the range. Accordingly the position of the distributorsegments mid-way between the points where the lamps are extinguished isthe proper position for reliable decoding of the signals.

It will be apparent from the above description that the combination ofthe glow discharge tubes with the operating circuits in the manner shownpermits the phase and range finding operation to be performed by one whois tending the distributor itself, irrespective of the location of theprinter. In fact, by placing the indicator lamps 32, 3 1 and 36 inproximity to the distributor it is possible to locate the printer at anyconvenient point whether near to or remote from the distributor.

Other applications of my invention besides those specifically shown anddescribed may be understood as comprehended within the scope of theinvention. The invention itself is, therefore, limited only as definedby the claims.

I claim:

1. In combination with a receiving distributor having a plurality ofconductive segments each appropriate to one of the respective units ofan .equal length code signal, printing telegraph apparatus having signalde-coding means connected in parallel circuits each of which includes arespective one of said segments, a'plurality of glow discharge tubes,circuits individually connected between respective ones of said tubesand such of said segments as are spaced apart by intervening conductivesegments, a source of operating potential, and signal-responsive relaymeans for selectively applying current to said circuits thereby toactuate both the signal de-coding means and the glow discharge tubes.

2. The combination according to claim 1 and including a unitary mountingmeans for said dis,- tributor segments, said mounting means beingmarking units for causing one or more of said tubes to glow, and meansincluding a brush rotatable over said segments and operative when saidsegment supporting means has been oriented to the point where the testsignal causes all of said tubes to glow, for passing each markingimpulse of a character code signal of uniform length through appropriatesegments of said series to the respective de-coding magnets for 10 whichsaid impulses are intended.

JAMES A. SPENCER.

